Apparatus for winding yarn

ABSTRACT

A system to control yarn tension in a multiposition winding apparatus in which a plurality of tension transducers are associated with preselected yarn lines for generating output signals indicative of yarn tension. A comparator controller system is coupled to the transducers to process and combine the transducer output signals to provide an error signal. A control unit responsive to the error signal changes the output of the windup motor power supply which, in turn, changes motor speed and, consequently, yarn tension. Circuitry is provided to monitor the error signal and inactivate the control unit if the error signal exceeds predetermined limits.

United States Patent Cole [54] APPARATUS FOR WINDING YARN [72] Inventor: Harold Wade Cole, Donelson, Tenn.

[73] Assignee: E. l. du Pont de Nemours and Company,

Wilmington, Del.

[22] Filed: Aug. 12, 1970 [21] Appl. No.2 63,102

[ Feb. 1,1972

3,563,485 2/1971 Phillips ..318/7 X Primary Examiner-Stanley N. Gilreath Assistant Examiner-Milton Gerstein Attorney-Howard P. West, Jr.

[5 7] ABSTRACT A system to control yarn tension in a multiposition winding apparatus in which a plurality of tension transducers are as sociated with preselected yarn lines for generating output signals indicative of yarn tension. A comparator controller system is coupled to the transducers to process and combine the transducer output signals to provide an error signal. A control unit responsive to the error signal changes the output of the windup motor power supply which, in turn. changes motor speed and, consequently, yarn tension. Circuitry is provided to monitor the error signal and inactivate the control unit if the error signal exceeds predetermined limits.

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J I9 IISAC INVENTOR HAROLD WADE COLE BY Ida/141% ATTORNEY PATENTED FEB 1 m2 SHEET 2 BF 2 INVENTOR HAROLD WADE COLE BY W7QQXMZX$ ATTORNEY APPARATUS FOR WlNDING YARN BACKGROUND OF THE INVENTION The present invention generally relates to a yarn-winding apparatus and, more particularly, it relates to a system for controlling yarn-winding tension in a multiple position winding apparatus.

In the winding of yarn into packages, it is highly desirable to maintain windup tension constant because the inability to accurately control tension can lead to poor package formation. Heretofore, systems for controlling winding tension have not been entirely satisfactory where position-to-positioh variations in a multiple position winding apparatus must be taken into consideration.

Most of the known devices for regulating yarn-winding tensions are for a single position and include a centrally pivoted swinging arm carrying a thread-line-engaging roller at one end and mechanically linked to a speed control apparatus for the motor at the other end. 1

Currently used high-speed winding techniques require far more sensitivity and less reaction time for windup tension control systems than afforded by those disclosed in the prior art. In addition, it is highly desirable to provide accurate regulation of as many positions as possible with the least possible investment in equipment for such regulation. The present invention fulfills these needs.

SUMMARY OF THE INVENTION In a yarn-winding machine having a plurality of positions each including a roll driven by an electric motor and a package support driven by the roll, there is provided a system for regulating the tension of yarn advancing from a source at a substantially constant speed around the roll to the support. The system includes a plurality of sensors for detecting tension at some of the positions, monitoring devices associated with each sensor for generating first signals related to the magnitude of the tension, a comparator means for combining and averaging those first signals that fall within predetermined limits into a second signal and a control unit responsive to the second signal for changing the output of the motor power supply means for regulating motor speed. There is also provided auxiliary means for comparing the second signal with the predetermined limits and generating a third signal when the second signal exceeds the limits which is used to deactivate the control unit for a period of time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic side elevation of yarn being wound into a package using a four-position windup tension control system for a multiposition windup.

FIG. 2 is a block diagram of the comparator controller of FIG. 1.

FIG. 3 is a schematic diagram of one of the comparators of FIG. 2.

FIG. 4 is a schematic diagram of the servocontrol unit of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, it will be seen that the windup chosen for purposes of illustration generally includes as components thereof a traverse cam 20, a surface drive roll 14, swing arm 32 mounted for relative rotation about pivot 30 and rotatably supporting bobbin 16, and a reciprocating traverse guide 12 driven by cam 20 through which yarn l advances from a source (not shown) and thence, under drive roll 14 to package 18. Motors 22, 24 along with belts 26, 28 are used to drive traverse cam and drive roll 14, respectively. Motors 24, 24', 24", 24" are synchronous motors representing a multiposition windup and their speeds are controlled by solidstate power supply 25. The key elements of the tension control system involve a tensiometer, a logic controller and a servo unit. Depending on the number of winding positions involved, one tensiometer on about one in four positions provides for satisfactory system operation.

For purposes of illustration, a four tensiometer control system is shown and includes as its major components tensiometers 11 110, connected to comparator controller unit 15 via respective leads 1343c and servocontrol unit 17, having its input connected to comparator unit 15 through leads 19, 21 and its output connected to power supply 25 by means of lead 23.

Tensiometers ll-llc are tension transducers that use the principle of electrical resistance strain gauges to convert deformation of an elastic sensing arm to linearly related changes in electrical resistance of the gauges. These resistance changes are then converted to electrical signals indicative of tension via standard electronic equipment. These signals are then fed over lines 13-130 to comparator controller unit 15.

Referring now to FIG. 2, comparator controller unit 15 is seen to include comparators 40-43 connected to averaging circuit 50 and to the output of tensiometers ll-l 1c via leads 13-130, an error amplifier 52 connected between output lead 51 of the averaging circuit and output lead 21 of the comparator controller. Average comparator 44 is also connected to the output of averaging circuit 50 and activates time delay relay 54 through which the voltage supply being fed to servo unit 17 over lead 19 may be interrupted.

One type of comparator circuit is used for comparators 4044 and is illustrated in FIG. 3. Two differential input highgain amplifiers 56, 58 are connected so that if a first signal fed to the amplifiers from tensiometer 11 (via lead 13) is within the predetermined limits established by the high and low set potentiometers 45, 46 connected to amplifiers 56, 58, respectively, relay 60 is actuated closing contacts 64 which feeds the first signal to the averaging circuit 50 consisting of resistors 53. The first signals are averaged and combined in circuit 50 into a second signal which drives error amplifier 52 that, in turn, responds to the difference between the average signal appearing on lead 51 and a set point signal obtained from potentiometer 55 (FIG. 2).

The servocontrol unit as shown in FIG. 4, includes a voltage amplifier 70 connected to a dead-band sensor amplifier 72 and a polarity amplifier 74 which, in turn, operate relays 76, 78 and their associated contacts 76a and 78a, 78b in the powerline to servomotor 80. The dead-band amplifier 72 and associated circuitry prevents small unnecessary speed changes. A clutch 82 is coupled between motor 80 and output potentiometer 84. In addition, motor 80 also positions feedback potentiometer 86. Power is supplied to servomotor 80 from time delay relay 54 over lead 19.

Average comparator 44 responds to second signals appearing at the output of averaging circuit 50 which exceed the high or low limits established by potentiometers 45, 46 and feeds a signal to relay 54.

In operation, tensiometers ll-llc send output signals to comparators 4043 which, in turn, reject any unreasonable signals. Those signals not rejected are averaged in circuit 50 to provide a second signal used to drive amplifier 52, which responds to the difference between the second signal and a set point established by potentiometer 55. The amplified error signal is fed over lead 21 to the servocontrol unit which through motor 80, clutch 82 and associated circuitry, translate the voltage level of the error signal into output potentiometer 84 position. The potentiometer 84 is connected to power supply 25 so that it can change the output of the power supply a limited amount to change the speed of motor 24 and stabilize windup tension at the level of the set point 55.

In the event the average tension signal or second signal becomes unreasonable with respect to the predetermined limits established by potentiometers 45, 46 (e.g., all positions with tensiometers are down-all tensiometers read zero), average comparator 44 generates a third signal which actuates time delay relay 54 that, in turn, cuts off the power to motor 80. This prevents any further change in the setting of potentiometer 84 and the output of power supply 25. Relay 54 delays restoration of power to servomotor 80 for a fixed period of time after the averaged or second signal becomes reasonable or within limits to allow the system circuits time to readjust.

While the preferred embodiment describes the use of a servocontrol unit as the final control element for the power supply, it is to be understood that in some applications, a computer may be used to perform the servocontrol unit function.

Although the windup chosen for purposes of illustration is one in which the package is surface driven by a motor-driven roll, the invention is equally applicable to other types of windups. For example, the package support or bobbin 16 could be directly driven by motor 24.

It is apparent that many changes and modifications of the disclosed control system may be made without departing from the spirit of the present invention which is accordingly intended to be limited only to the scope of the appended claims.

What is claimed is:

1. In a multiposition yarn-winding machine, each position including a package support driven by an electric motor, a common power supply means for regulating the speed of the motors, a system for regulating the tension in yarns advancing at a substantially constant speed from a source to said supports comprising: a plurality of sensors for detecting yarn tening devices for combining said first signals that fall within predetermined limits into a second signal; a control unit connected to said power supply means and responsive to said second signal for changing the output of said power supply thereby changing the speed of the motors; and means for comparing said second signal with said predetermined limits and generating a third signal when said second signal exceeds said limits, said control unit being inactivated by said third signal.

2. The system as defined in claim 1, including a time delay device connected between the means for generating the third signal and the control unit for delaying activation of the control unit by said second signal after it has been deactivated by said third signal.

3. The system as defined in claim I, said control unit being a servocontrol unit including a servomotor coupled to a potentiometer, said potentiometer having an output lead connected to said power supply means.

4. The yarn-winding machine as defined in claim 1, each position including a roll driven by said electric motor for driving said package support, said yarn advancing around said roll to said support. 

1. In a multiposition yarn-winding machine, each position including a package support driven by an electric motor, a common power supply means for regulating the speed of the motors, a system for regulating the tension in yarns advancing at a substantially constant speed from a source to said supports comprising: a plurality of sensors for detecting yarn tension at some of said positions; monitoring devices coupled to each sensor for generating first signals related to the magnitude of said yarn tension; means connected to said monitoring devices for combining said first signals that fall within predetermined limits into a second signal; a control unit connected to said power supply means and responsive to said second signal for changing the output of said power supply thereby changing the speed of the motors; and means for comparing said second signal with said predetermined limits and generating a third signal when said second signal exceeds said limits, said control unit being inactivated by said third signal.
 2. The system as defined in claim 1, including a time delay device connected between the means for generating the third signal and the control unit for delaying activation of the control unit by said second signal after it has been deactivated by said third signal.
 3. The system as defined in claim 1, said control unit being a servocontrol unit including a servomotor coupled to a potentiometer, said potentiometer having an output lead connected to said power supply means.
 4. The yarn-winding machine as defined in claim 1, each position including a roll driven by said electric motor for driving said package support, said yarn advancing around said roll to said support. 